(CNN) -- Public health officials in and around Chicago, Illinois, announced Friday they are offering testing to hundreds of patients and staff members at three area hospitals who may have been exposed to tuberculosis by a doctor who was recently diagnosed with an active case of the disease.

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The infected first-year pediatric resident, who is in her 20s, was diagnosed Tuesday with a confirmed case of tuberculosis, said Tim Hadic, a spokesman for the Chicago Department of Public Health.

"Right now, the three hospitals are going back into their records and contacting anybody who may have had significant contact with her, from November to April 1st," he said. "They're contacting literally hundreds of people, just alerting them to the situation."

He added, "It's a cause for concern, but certainly not a cause for alarm."